This invention relates to methods of treating traumatic brain injury (TBI), ischemic stroke, or hypoxic brain injury, comprising administering to a patient in need of such treatment an NR2B subtype selective N-methyl-D-aspartate (NMDA) receptor antagonist in combination with one or more other compounds that protect neurons from toxic insult, inhibit the inflammatory reaction after brain damage or promote cerebral reperfusion.
More specifically, this invention relates to methods of treating traumatic brain injury (TBI) or hypoxic or ischemic stroke, comprising administering to a patient in need of such treatment an NR2B subtype selective N-methyl-D-aspartate (NMDA) receptor antagonist in combination with either: (a) a neutrophil inhibitory factor (NIF); (b) a sodium channel antagonist; (c) a nitric oxide synthase (NOS) inhibitor; (d) a glycine site antagonist; (e) a potassium channel opener; (f) an AMPA/kainate receptor antagonist; (g) a calcium channel antagonist; (h) a GABA-A receptor modulator (e.g., a GABA-A receptor agonist); (i) an antiinflammatory agent; or (j) a matrix metalloprotease (MMP) inhibitor.
Brain and spinal cord injury caused by stroke, trauma or hypoxia often result in lifelong disability and premature death. The cause of disability and death is the disruption of function and frank death of neurons and other cells in the central nervous system. Therefore, a clear benefit is anticipated from therapies that reduce or prevent neuronal dysfunction and death after ischemic, hypoxic or traumatic CNS insult.
One of the causes of neuronal dysfunction and death after CNS insult is toxicity caused by a prolonged elevation of glutamate and other excitatory amino acids (EAAs) and overactivation of the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors. Glutamate and other EAAs play dual roles in the central nervous system as essential amino acids and the principal excitatory neurotransmitters. There are at least four classes of EAA receptors, specifically NMDA, AMPA (2-amino-3-(methyl-3-hydroxyisoxazol-4-yl)propanoic acid), kainate and metabotropic. These EAA receptors mediate a wide range of signaling events that impact all physiological brain functions. As neurotransmitters, EAAs are released from postsynaptic nerve terminals and then are rapidly resequestered by a variety of cellular reuptake mechanisms. Consequently, the physiological levels of EAAs in the brain parenchyma are maintained at a low level. However, after a CNS insult, the levels of EAAs in the parenchyma increase dramatically and may remain elevated for periods of hours to days. This results in pathological overactivation of EM receptors and neuronal dysfunction and death.
Several lines of evidence suggest that the NMDA subtype of glutamate receptor is the principal mediator of the EAA-induced toxicity described above. Neurons in primary culture are exquisitely sensitive to the toxic effects of NMDA receptor activation and NMDA receptor antagonists protect cultured neurons from both NMDA and glutamate toxicity (Choi et al., J. Neurosci., 1988, 8, 185-196; Rosenberg et al., 1989, Neurosci. Lett. 103, 162). NMDA receptors are also implicated as mediators of neurotoxicity in vivo since NMDA receptor antagonists can reduce neuron loss in animal models of focal ischemia (McCulloch, J. Neural. Trans., 1994, 71-79) and head trauma (Bullock et al., Acta Neurochir., 1992, 55, 49-55). The neuroprotective effect of NMDA receptor inhibition is realized with several different classes of compounds that target different sites on the NMDA receptor-channel complex. These include competitive antagonists at the glutamate binding site such as (R,E)-4-(3-phosphonoprop-2-enyl) piperazine-2-carboxylic acid (d-CPPene) (Lowe et al., 1994, Neurochem Int. 25, 583) and cis-4-phosphonomethyl-2-piperidine carboxylic acid (CGS-19,755) (Murphy et al., 1988, Br. J. Pharmacol. 95, 932) and competitive antagonists at the glycine co-agonist (Johnson et al., Nature, 1987, 327, 529-531; and Kemp et al., Trends Pharmacol. Sci., 1993, 14, 20-25) binding site such as 5,7-dichloro-4S-(3-phenyl-ureido)-1,2,3,4-tetrahydro-quinoline-2R-carboxylic acid (L-689,560) and 5-nitro-6,7-dichloro-1,4-dihydro-2,3-quinoxalinedione (ACEA-1021) (Leeson et al., 1994, J. Med. Chem. 37, 4053). Compounds have also been identified which block the NMDA receptor-gated ion channel, including phencyclidine (PCP), (+)-5-methyl-10,11-dihydro-5-H-dibenzo[a,d]cycloheptan-5,10-imine (MK-801) (Kemp et al., 1987, Trends in Neurosci. 10, 294), and C-(1-napthyl-Nxe2x80x2-(3-ethyl phenyl)-Nxe2x80x2-methyl guanidine hydrochloride (CNS-1102) (Reddy et al., 1994, J. Med. Chem. 37, 260).
The neuroprotective effect of NMDA receptor antagonists in experimental systems has prompted considerable interest in the therapeutic potential of this type of compound. Several prototype antagonists have been progressed into clinical trials, especially for stroke and head trauma (Muir et al., 1995, Stroke 26, 503-513). However, side effects at therapeutic drug levels have been a significant problem that has hindered the development process (Muir et al., supra). In particular, both glutamate competitive antagonists and channel blocking agents cause cardiovascular effects and psychotic symptoms in man. Although the physiological basis for these side effects are not yet understood, in rodents these types of compounds also cause locomotor hyperactivity and a paradoxical neuronal hyperexcitability manifest as neuronal vacuolization in cingulate and retrosplenial cortices (Olney et al., 1991, Science, 254, 1515-1518). Antagonists at the glycine coagonist site cause less locomotor activation and do not cause neuronal vacuolization at neuroprotective doses in rodents, suggesting that this class of antagonists may be better tolerated in man (Kemp et al., 1993, Trends Pharmacol. Sci. 14, 20-25). Unfortunately, physicochemical problems associated with the quinoxalinedione nucleus (solubility, brain penetration, protein binding) have hindered efforts to bring this class forward in the clinic.
The compound (1S,2S)-1-(4-hydroxyphenyl)-2-(4-hydroxy-4-phenylpiperidino)-1-propanol) (hereinafter referred to as xe2x80x9cCompound Axe2x80x9d) represents a fourth mechanistic class of NMDA receptor antagonist. This class is unique in that it is specific for a subtype of NMDA receptor, those containing the NR2B subunit that is expressed in the forebrain. As with other ligand gated ion channels, the functional NMDA receptor is composed of multiple protein subunits. Five subunits have been cloned to date, NR1 (of which there are eight splice variants) and NR2A-D. Expression studies indicate a composition of at least one NR1 subunit and one or more of the NR2 subunits (Monyer et al., Science, 1992, 256, 1217-1221; Kutsuwada et al., 1992, Nature 358, 36; and Chazot et al., 1994, J. Biol. Chem. 269, 24403). In situ hybridization and immunohistochemistry studies indicate that subunits are widely and differentially distributed throughout the brain (Monyer et al., Neuron, 1994, 12, 529-540; Kutsuwada et al., supra; Ishii et al., 1993, J. Biol. Chem. 268, 2836; Wenzel et al., 1995, NeuroReport 7, 45).
Compound A and other structurally related compounds have been found to be functionally selective for NMDA receptors containing the NR2B subunit. The fact that this class of NMDA receptor antagonist is neuroprotective in a variety of in vitro and in vivo experimental models (Chenard and Menniti, 1999, Current Pharmaceutical Design 5, 381-404; Di et al., 1997, Stroke 28, 2244-2251; Okiyama et al., 1998, Brain Res. 792, 291-298; Okiyama et al., 1997, J. Neurotrauma 14, 211-222; Tsuchida et al., 1997, Neurotrama 14, 409-417) suggests that NR2B subunit containing NMDA receptors are prominently involved in the EAA-induced toxic cascade. Furthermore, antagonists selective for NR2B subunit containing NMDA receptors have been found to produce less toxic side effects in animals and in man than other classes of NMDA receptor antagonists and can be selected for excellent pharmaceutical properties. Thus, certain cardiovascular and behavioral adverse side effects that are exhibited upon administration of therapeutically effective dosages of subunit nonselective NMDA receptor antagonists can be eliminated or significantly reduced by the use, in therapeutically effective dosages, of NR2B subtype selective NMDA receptor antagonists. The NMDA antagonists employed in the methods and pharmaceutical compositions of the present invention are preferably those that exhibit selectivity for the NR2B subunit containing NMDA receptors.
Selectivity of compounds for the NR2B-subunit containing NMDA receptor is defined as an affinity for the racemic [3H](+)-(1S, 2S)-1-(4-hydroxy-phenyl)-2-(4-hydroxy-4-phenylpiperidino)-1-propanol binding site in forebrain of rats, as described by Chenard and Menniti (Antagonists Selective for NMDA receptors containing the NR2B Subunit, Current Pharmaceutical Design, 1999, 5:381-404). This affinity is assessed in a radioligand binding assay as described later in this application. Selective compounds are those which displace specific binding of racemic [3H]CP-101,606 from rat forebrain membranes with an IC50xe2x89xa65 xcexcM.
A number of the compounds with selectivity for the NR2B subtype of NMDA receptor also interact with and inhibit a number of other receptors and ion channels. For example, ifenprodil inhibits the xcex11 adrenergic receptor with an affinity similar to that at which the compound inhibits NR2B subtype NMDA receptors. Inhibition of xcex11 adrenergic receptors is related to particular structural features of ifenprodil and related molecules (Chenard, et al., J. Med. Chem., 1991, 34, 3085-3090 (1991). It is well known that compounds that block xcex11 adrenergic receptors (prazosin, for example) are associated with blood pressure lowering actively, an activity that is contraindicated for drugs used treat stroke, TBI and related conditions. Therefore, the NMDA antagonists employed in the methods and pharmaceutical compositions of the present invention preferably are those that exhibit selectivity for the NR2B subunit containing NMDA receptors over that for xcex11 adrenergic receptors, specifically, those having a ratio of NR2B receptor selectivity to xcex11 adrenergic receptor selectivity of at least about 3:1. More preferably, such ratio is at least 5:1.
The present invention relates to the additional therapeutic benefits that may be gained by treating traumatic brain injury, stroke, or hypoxic brain injury with an NR2B subtype selective NMDA receptor antagonist in combination with other types of compounds. These include compounds that protect neurons from toxic insult, inhibit the inflammatory reaction after brain damage and/or promote cerebral reperfusion. Although NMDA receptor-mediated toxicity is a principal cause of the neuronal dysfunction and death that occurs after CNS insult, additional mechanisms also participate. By reducing the pathological consequences of these additional mechanisms, the overall benefit of the therapeutic intervention may be increased. Furthermore, inhibiting multiple pathological processes may provide an unexpected synergistic benefit over and above that which may be achievable alone with the use of an NMDA receptor antagonist.
During the course of an ischemic, hypoxic, or traumatic injury to the CNS a number of toxic products are formed which can further damage brain cells injured by the primary pathological process or produce damage in cells that otherwise escape damage from the primary insult. These toxins include, but are not limited to: nitric oxide (NO); other reactive oxygen and nitrogen intermediates such as superoxide and peroxynitrite; lipid peroxides; TNFxcex1, IL-1 and other interleukins, cytokines or chemokines; cyclooygenase and lipoxygenase derivatives and other fatty acid mediators such as leukotrienes, glutamate and prostaglandins; and hydrogen ions. Inhibiting the formation, action or accelerating the removal of these toxins may protect CNS cells from damage during an ischemic, hypoxic or traumatic injury. Furthermore, the beneficial effects of inhibiting the formation, action or accelerating the removal of these toxins may be additive or synergistic with the benefits of inhibiting NR2B subunit containing NMDA receptors with a NR2B subunit selective NMDA receptor antagonist. Examples of compounds that inhibit the formation or action of these toxins, or accelerate their removal include, but are not limited to, antioxidants, neutrophil inhibitory factors (NIF""s), sodium channel antagonists, NOS inhibitors, potassium channel openers, glycine site antagonists, potassium channel openers, AMPA/kainate receptor antagonists, calcium channel antagonists, GABA-A receptor modulators (e.g., GABA-A receptor agonists), and antiinflammatory agents.
The formation and release of many of the toxins listed above are triggered by physiological signaling mechanisms that become pathologically activated by ischemic, hypoxic or traumatic CNS injury. Activation of these signaling mechanisms can also result in cellular depolarization. This depolarization may disrupt cellular ionic homeostasis, accelerate the rate of energy utilization as the cell strives to maintain homeostasis, and/or further accelerate the rate of formation and release of toxins. Thus, inhibition of these signaling mechanisms during ischemic, hypoxic or traumatic CNS injury may reduce the degree of cellular dysfunction and death. Furthermore, the beneficial effects of inhibiting these signaling mechanisms may be additive or synergistic with the benefits of inhibiting NR2B subunit containing NMDA receptors with a NR2B subunit selective NMDA receptor antagonist. These signaling mechanisms include, but are not limited to: NMDA receptors other than those containing the NR2B subunit; other EAA receptors such as AMPA, KA, or metabotropic receptors; other ligand-gated ion channels which promote depolarization and/or toxin release; voltage gated calcium channels including those of the L-, P-, Q/R-, N-, or T-types; voltage gated sodium channels. Examples of compounds that inhibit these signaling pathways include, but are not limited to, AMPA/kainate receptor antagonists, sodium channel antagonists and calcium channel antagonists.
Another approach to inhibiting cellular depolarization caused by ischemic, hypoxic or traumatic CNS injury and the resultant deleterious effects is to activate signaling pathways that oppose those causing depolarization. Again, the beneficial effects of activating these signaling mechanisms may be additive or synergistic with the benefits of inhibiting NR2B subunit containing NMDA receptors with a NR2B subunit selective NMDA receptor antagonist. These signaling mechanisms include, but are not limited to: GABAA receptor activation; voltage or ligand gated potassium channel activation; voltage or ligand gated chloride channel activation. Examples of compounds that activate these signaling pathways include, but are not limited to, potassium channel openers and GABA-A receptor agonists.
Excessive cellular depolarization and the loss of ionic homeostasis can lead to the loss in the ability of a cell to maintain physical integrity and cellular death ensues by a process often termed necrotic cell death. However, ischemic, hypoxic or traumatic CNS injury can also induce in many cells the activation of another mechanism causing cellular death that is termed apoptosis. The relationship between necrotic and apoptotic cell death is not fully understood and in pathological conditions such as ischemic, hypoxic or traumatic CNS injury both necrotic and apoptotic mechanisms leading ultimately toward cell death may be at play. Regardless of the specifics of this interrelationship, it has been suggested that inhibition of apoptotic mechanism of cell death may have a therapeutic benefit in ischemic, hypoxic or traumatic CNS injury. The beneficial effects of inhibiting apoptosis during ischemic, hypoxic or traumatic CNS injury may be additive or synergistic with the benefits of inhibiting NR2B subunit containing NMDA receptors with a NR2B subunit selective NMDA receptor antagonist. Apoptotic mechanisms include, but are not limited to: activation of FAS/TNFxcex1/p75 receptors; activation of caspases including caspases 1 through 9; activation of NFxcexaB; activation of the JNK and/or p38 kinase signaling cascades; inhibition of mitochondrial disruption and the activation of the mitochondrial permeability transition pore; activation of intracellular proteases such as the calpains. Examples of compounds that inhibit these apoptotic mechanisms include, but are not limited to, caspase inhibitors and inhibitors of the other enzymes mentioned above as mediators of apoptotic mechanisms
Cells in the CNS are highly dependent on cell-to-cell interactions and interaction with the extracellular matrix for survival and proper function. However, during ischemic, hypoxic, or traumatic CNS insult these interactions are often disrupted and this can lead directly to or contribute to cellular dysfunction and death. Thus, therapies that maintain cell-to-cell and cell-to-extracellular matrix interaction during ischemic, hypoxic or traumatic CNS insult are expected to reduce dysfunction and cell death. Furthermore, the beneficial effects of therapies that maintain cell-to-cell and cell-to-extracellular matrix interaction during ischemic, hypoxic or traumatic CNS injury may be additive or synergistic with the benefits of inhibiting NR2B subunit containing NMDA receptors with a NR2B subunit selective NMDA receptor antagonist. Mechanisms that contribute to the disruption of cell-to-cell and cell-to-extracellular matrix interaction during ischemic, hypoxic or traumatic CNS insult include, but are not limited to, the activation of proteases which degrade the extracellular matrix. These include, but are not limited to, matrix metalloproteases such as MMP 1 through 13. Examples of compounds that inhibit these enzymes include, but are not limited to those referred to in the following patents and patent applications: U.S. Pat. No. 5,861,510, issued Jan. 19, 1999; European Patent Application EP 606,046, published Jul. 13, 1994; European Patent Application EP 935,963, published Aug. 18, 1999; PCT Patent Application WO 98/34918, published Aug. 13, 1998; PCT Patent Applications WO 98/08825 and WO 98/08815, both published Mar. 5, 1998; PCT Patent Application WO 98/03516, published Jan. 29, 1998; and PCT Patent Application WO 98/33768, published Aug. 6, 1998. The foregoing patents and patent applications are incorporated herein by reference in their entireties.
CNS ischemia, hypoxia, or trauma leads to an inflammatory response mediated by various components of the innate and adaptive immune system. Because of the nature of the CNS and its unique relationship to the immune system, the immune system activation caused by CNS ischemia, hypoxia, or trauma can exacerbate cellular dysfunction and death. The mechanisms whereby immune activation exacerbates CNS injury are many-fold. Immune cells resident to the CNS, such as astrocytes and microglia, are activated following CNS injury. Furthermore, peripheral immune cells are recruited to enter the CNS and also become activated. These cells include monocytes/macrophages, neutrophils, and T lymphopcytes. Recruitment and activation of these peripheral immune cells into the CNS after injury involves many of the same mechanisms by which these cells are recruited to and activated by injured tissue outside the CNS. The cell within the area of tissue injury and the vasculature around the site of injury begins to elaborate proteins that signal to immune cells circulating in the blood stream. These cells then adhere to the vascular epithelium and enter the area in and around the damaged tissue. These activated immune cells then promote many of the deleterious events listed above, including release of a variety of toxins and disruption of cell-to-cell and cell-to-extracellular matrix interactions.
Thus, inhibition of immune cell recruitment, adherence to the vasculature, activation, and formation and release of toxins and proteases in response to CNS ischemia, hypoxia, or trauma is hypothesized to reduce the cellular dysfunction and death caused by these CNS insults. The beneficial effects of inhibiting immune cell recruitment, activation, and formation and release of toxins and proteases during ischemic, hypoxic or traumatic CNS injury may be additive or synergistic with the benefits of inhibiting NR2B subunit containing NMDA receptors with a NR2B subunit selective NMDA receptor antagonist. Compounds that inhibit immune cell recruitment include, but are not limited to, antagonists to a wide variety of cytokine and chemokine receptors. Compounds that inhibit immune cell adherence to the vasculature include, but are not limited to, NIF""s and antibodies to a variety of cell adhesion molecules. Compounds that inhibit immune cell activation include, but are not limited to, antagonists to a wide variety of cytokine and chemokine receptors, NIF""s and antibodies to a variety of cell adhesion molecules, antagonists of intracellular enzymes involved in transducing the activating signal into a cellular response such as antagonists of COX and COX2, various protein ser/thr and tyr kinases and intracellular proteases. Recruitment, adherence, and activation of CNS resident and peripheral immune cells can also be inhibited by the activation of cell signaling pathways that oppose this activation. Compounds that activate such signaling pathways include, but are not limited to, PPARxcex3 activators.
This invention also relates to a method of treating traumatic brain injury or hypoxic or ischemic stroke in a mammal, including a human, comprising administering to said mammal:
(a) a neutrophil inhibiting factor (NIF) or a pharmaceutically acceptable salt thereof; and
(b) an NR2B subtype selective NMDA receptor antagonizing receptor compound or a pharmaceutically acceptable salt thereof;
wherein the active agents xe2x80x9caxe2x80x9d and xe2x80x9cbxe2x80x9d above are present in amounts that render the combination of the two agents effective in treating hypoxic or ischemic stroke.
This invention also relates to a pharmaceutical composition for treating traumatic brain injury or hypoxic or ischemic stroke in a mammal, including a human, comprising:
(a) a neutrophil inhibiting factor (NIF) or a pharmaceutically acceptable salt thereof;
(b) an NR2B subtype selective NMDA receptor antagonizing compound or a pharmaceutically acceptable salt thereof; and
c) a pharmaceutically acceptable carrier;
wherein the active agents xe2x80x9caxe2x80x9d and xe2x80x9cbxe2x80x9d are present in such composition in amounts that render the combination of the two agents effective in treating such disorder.
Neutrophil Inhibitory Factors (NIF) are proteins that are specific inhibitors of neutrophil activity, in particular of the adhesion of neutrophils to vascular endothelial cells, and which are derived from hookworms and related species, and which can be isolated from natural sauces or made by recombinant methods, and which when isolated from parasitic worms, are glycoprotiens, and that are not members of the integrin or selection families of proteins and also are not members of the immunoglobutin superfamily of adhesive proteins.
Neutrophils are a subclass of the class of cells known as granulocytes, which are a subclass of the class of cells known as leukocytes. Neutrophils are an essential component of the host defense system against microbial invasion. In response to soluble inflammatory mediators released by cells at the site of injury, neutrophils emigrate into tissue from the bloodstream by crossing the blood vessel wall. At the site of injury, activated neutrophils kill foreign cells by phagocytosis and by the release of cytotoxic compounds, such as oxidants, proteases and cytokines. Despite their, importance in fighting infection, neutrophils themselves can promote tissue damage. During an abnormal inflammatory response, neutrophils can cause significant tissue damage by releasing toxic substances at the vascular wall or in uninjured tissue. Alternatively, neutrophils that stick to the capillary wall or clump in venules may produce tissue damage by ischemia. Such abnormal inflammatory responses have been implicated in the pathogenesis of a variety of clinical disorders including adult respiratory distress syndrome (ARDS); ischemia-reperfusion injury following myocardial infarction, shock, stroke, and organ transplantation; acute and chronic allograft rejection; vasculitis; sepsis; rheumatoid arthritis; and inflammatory skin diseases (Harlan et al., 1990, Immunol. Rev. 114, 5).
Neutrophil adhesion at the site of inflammation is believed to involve at least two discrete cell-cell interactive events. Initially, vascular endothelium adjacent to inflamed tissue becomes sticky for neutrophils; neutrophils interact with the endothelium via low affinity adhesive mechanisms in a process known as xe2x80x9crollingxe2x80x9d. In the second adhesive step, rolling neutrophils bind more tightly to vascular endothelial cells and migrate from the blood vessel into the tissue.
Neutrophil inhibitory factors are described in greater detail, along with methods of isolating them from natural sources and of cloning them, in U.S. Pat. No. 5, 919,900, which issued in Jul. 6, 1999, U.S. Pat. No. 5,747,296, which issued on May 5, 1998, and U.S. Pat. No. 5,789,178, which issued in Aug. 4, 1998. These three patents are incorporated herein by reference in their entirety. Examples of NIF""s suitable for use in the pharmaceutical compositions and methods of the present invention are those referred to in U.S. Pat. No. 5,919,900, referred to above. Such NIF""s include certain glycoproteins isolated from nematodes and other parasitic worms, as well as certain recombinant non-glycosylated proteins. Preferred NIF""s for use in the pharmaceutical compositions and methods of this invention are those that are designated as preferred in U.S. Pat. No. 5,919,900, referred to above.
The inhibition of neutrophil activity by NIF""s suitable for use in the compositions and methods of the present invention includes but is not limited to inhibition of one or more of the following activities of neutrophils: release of hydrogen peroxide, release of superoxide anion, release of myeloperoxidase, release of elastase, homotypic neutrophil aggregation, adhesion to plastic surfaces, adhesion to vascular endothelial cells, chemotaxis, transmigration across a monolayer of endothelial cells and phagocytosis. Preferred assays for determining the neutrophil inhibitory activity of a substance include those where inhibition of neutrophil activity is demonstrated by an in vitro assay that determines adhesion to neutrophils to vascular endothelial cells, release of hydrogen peroxide from neutrophils, homotypic neutrophil aggregation or adhesion of neutrophils to vascular plastic surfaces.
The term xe2x80x9ctreatingxe2x80x9d, as used herein, refers to retarding or reversing the progress of, or alleviating or preventing either the disorder or condition to which the term xe2x80x9ctreatingxe2x80x9d applies, or one or more symptoms of such disorder or condition. The term xe2x80x9ctreatmentxe2x80x9d, as used herein, refers to the act of treating a disorder or condition, as the term xe2x80x9ctreatingxe2x80x9d is defined above.
Preferred methods and pharmaceutical compositions of this invention include the above described methods and pharmaceutical compositions wherein the NMDA receptor antagonist is an NR2B subtype selective NMDA receptor antagonist of the formula 
or a pharmaceutically acceptable acid addition salt thereof, wherein:
(a) R2 and R5 are taken separately and R1, R2, R3 and R4 are each independently hydrogen, (C1-C6) alkyl, halo, CF3, OH or OR7 and R5 is methyl or ethyl; or
(b) R2 and R5 are taken together and are 
forming a chroman-4-ol ring, and R1, R3 and R4 are each independently hydrogen, (C1-C6) alkyl, halo, CF3, OH or OR7;
R6 is 
R7 is methyl, ethyl, isopropyl or n-propyl;
R8 is phenyl optionally substituted with up to three substituents independently selected from (C1-C6) alkyl, halo and CF3;
X is O, S or (CH2)n; and
n is 0, 1, 2, or 3.
Compounds of formula I are described in U.S. Pat. Nos. 5,185,343; 5,272,160; 5,338,754; 5,356,905; and 6,046,213 (which issued, respectively, on Feb. 9, 1993, Dec. 21, 1993, Aug. 16, 1994, Oct. 18, 1994, and Apr. 4, 2000); U.S. patent applications Ser. Nos. 08/292,651 (filed Aug. 18, 1994), Ser. No. 08/189,479 (filed Jan. 31, 1994) and Ser. No. 09/011,426 (filed Jun. 20, 1996); PCT International Application No. PCT/IB95/00398, which designates the United States (filed May 26, 1995) (corresponding to WO 96/37222); and PCT International Application No. PCT/IB95/00380, which designates the United States (filed May 18, 1995) (corresponding to WO 96/06081). All of the foregoing patents, United States patent applications and PCT international application are herein incorporated by reference in their entirety.
Preferred compounds for use in the methods and pharmaceutical compositions of the present invention include those of formula I wherein R2 and R5 are taken separately; R2 and R3 are hydrogen; R6 is 
and R8 is phenyl, 4-halophenyl or 4-trifluoromethylphenyl. Within this group, more specific preferred compounds are those wherein R5 is methyl having a 1S*,2S* relative stereochemistry: 
Other preferred compounds for use in the methods and pharmaceutical compositions of the present invention include those of formula I wherein R2 and R5 are taken together and are 
forming a chroman-4-ol ring. Within this group, preferred compounds also include those wherein the C-3 and C-4 positions of said chroman-4-ol ring have a 3R*,4S* relative stereochemistry: 
Within this group, preferred compounds also include those wherein R6 is 
and R8 is phenyl or 4-halophenyl.
Compounds of formula I may contain chiral centers and therefore may exist in different enantiomeric and diastereomeric forms. This invention relates to the above methods of treatment using and the above pharmaceutical compositions comprising all optical isomers and all stereoisomers of compounds of the formula I and mixtures thereof.
The term xe2x80x9calkylxe2x80x9d, as used herein, unless otherwise indicated, includes saturated monovalent hydrocarbon radicals having straight, branched or cyclic moieties or combinations thereof.
The term xe2x80x9cone or more substituentsxe2x80x9d, as used herein, refers to a number of substituents that equals from one to the maximum number of substituents possible based on the number of available bonding sites.
The terms xe2x80x9chaloxe2x80x9d and xe2x80x9chalogenxe2x80x9d, as used herein, unless otherwise indicated, include chloro, fluoro, bromo and iodo.
Formula I above includes compounds identical to those depicted but for the fact that one or more hydrogen, carbon or other atoms are replaced by isotopes thereof. Such compounds may be useful as research and diagnostic tools in metabolism pharmacokinetic studies and in binding assays.
NMDA receptor antagonists of the formula I that are particularly preferred for use in the methods and pharmaceutical compositions of this invention are the following: (+)-(1S, 2S)-1-(4-hydroxy-phenyl)-2-(4-hydroxy-4-phenylpiperidino)-1-yl)-1-propanol; (1S,2S)-1-(4-hydroxy-3-methoxyphenyl)-2-(4-hydroxy-4-phenylpiperidino)-1-propanol; (1S,2S)-1-(4-hydroxy-3-methyl phenyl)-2-hydroxy-4-phenyl (piperidino)-1-propanol and (3R,4S)-3-(4-(4-fluorophenyl)-4-hydroxypiperidin-1-yl)-chroman-4,7-diol.
This invention also relates to a method of treating traumatic brain injury or hypoxic or ischemic stroke in a mammal, including a human, comprising administering to said mammal:
(a) a glycine site antagonizing compound (e.g., gavestinil) or a pharmaceutically acceptable salt thereof; and
(b) an NR2B subtype selective NMDA receptor antagonizing compound or a pharmaceutically acceptable salt thereof;
wherein the active agents xe2x80x9caxe2x80x9d and xe2x80x9cbxe2x80x9d above are present in amounts that render the combination of the two agents effective in treating hypoxic or ischemic stroke.
This invention also relates to a pharmaceutical composition for treating traumatic brain injury or hypoxic or ischemic stroke in a mammal, including a human, comprising:
(a) a glycine site antagonizing compound (e.g., gavestinil) or a pharmaceutically acceptable salt thereof;
(b) an NR2B subtype selective NMDA receptor antagonizing compound or a pharmaceutically acceptable salt thereof; and render the combination of the two agents effective in treating such disorder.
Examples of glycine site antagonists that are suitable for use in the pharmaceutical compositions and methods of this invention are those referred to in the following: U.S. Pat. No. 5,942,540, which issued on Aug. 24, 1999; World Patent Application WO 99/34790 which issued on Jul. 15, 1999; WO 98/47878, which was published on Oct. 29, 1998; World Patent Application WO 98/42673, which was published on October 1, 1998; European Patent Application EP 966475A1, which was published on Dec. 29, 1991; World Patent Application 98/39327, which was published on Sep. 11, 1998; World Patent Application WO 98/04556, which was published on Feb. 5, 1998; World Patent Application WO 97/37652, which was published on Oct. 16, 1997; U.S. Pat. No. 5,837,705, which was issued on Oct. 9, 1996; World Patent Application WO 97/20553, which was published on Jun. 12, 1997; U.S. Pat. No. 5,886,018, which was issued on Mar. 23, 1999; U.S. Pat. No. 5,801,183, which was issued on Sep. 1, 1998; World Patent Application WO 95/07887, which was issued on Mar. 23, 1995; U.S. Pat. No. 5,686,461, which was issued on Nov. 11, 1997; U.S. Pat. No. 5,614,509, which was issued on Mar. 25, 1997; U.S. Pat. No. 5,510,367, which was issued on Apr. 23, 1996; European Patent Application 517,347A1, which was published on Dec. 9, 1992; U.S. Pat. No. 5,260,324, which published on Nov. 9, 1993. The foregoing patents and patent applications are incorporated herein by reference in their entireties.
Other examples of glycine site antagonists that can be used in the pharmaceutical composition and methods of this invention are N-(6,7-dichloro-2,3-dioxo-1,2,3,4-tetrahydro-quinoxalin-5-yl)-N-(2-hydroxy-ethyl)-methanesulfonamide and 6,7-dichloro-5-[3-methoxymethyl-5-(1-oxy-pyridin-3-yl)-[1,2,4]triazol-4-yl]-1,4-dihydro-quinoxa-line-2,3-dione.
This invention also relates to a method of treating traumatic brain injury or hypoxic or ischemic stroke in a mammal, including a human, comprising administering to said mammal:
(a) a sodium channel blocking compound or a pharmaceutically acceptable salt thereof; and
(b) an NR2B subtype selective NMDA receptor antagonizing compound or a pharmaceutically acceptable salt thereof;
wherein the active agents xe2x80x9caxe2x80x9d and xe2x80x9cbxe2x80x9d above are present in amounts that render the combination of the two agents effective in treating hypoxic or ischemic stroke.
This invention also relates to a pharmaceutical composition for treating traumatic brain injury or hypoxic or ischemic stroke in a mammal, including a human, comprising:
(a) a sodium channel blocking compound or a pharmaceutically acceptable salt thereof;
(b) an NR2B subtype selective NMDA receptor antagonizing compound or a pharmaceutically acceptable salt thereof; and
c) a pharmaceutically acceptable carrier;
wherein the active agents xe2x80x9caxe2x80x9d and xe2x80x9cbxe2x80x9d are present in such composition in amounts that render the combination of the two agents effective in treating such disorder.
Examples of suitable sodium channel blocking compounds (i.e., sodium channel antagonists) that can be employed in the methods and pharmaceutical compositions of this invention, as described above, are ajmaline, procainamide, flecainide and riluzole.
This invention also relates to a method of treating traumatic brain injury or hypoxic or ischemic stroke in a mammal, including a human, comprising administering to said mammal:
(a) a calcium channel blocking compound or a pharmaceutically acceptable salt thereof; and
(b) an NR2B subtype selective NMDA receptor antagonizing compound or a pharmaceutically acceptable salt thereof;
wherein the active agents xe2x80x9caxe2x80x9d and xe2x80x9cbxe2x80x9d above are present in amounts that render the combination of the two agents effective in treating hypoxic or ischemic stroke.
This invention also relates to a pharmaceutical composition for treating traumatic brain injury or hypoxic or ischemic stroke in a mammal, including a human, comprising:
(a) a calcium channel blocking compound or a pharmaceutically acceptable salt thereof;
(b) an NR2B subtype selective NMDA receptor antagonizing compound or a pharmaceutically acceptable salt thereof; and
(c) a pharmaceutically acceptable carrier;
wherein the active agents xe2x80x9caxe2x80x9d and xe2x80x9cbxe2x80x9d are present in such composition in amounts that render the combination of the two agents effective in treating such disorder.
Examples of suitable calcium channel blocking compounds (i.e., calcium channel antagonists) that can be employed in the methods and pharmaceutical compositions of this invention, as described above, are diltiazem, omega-conotoxin GVIA, methoxyverapamil, amlodipine, felodipine, lacidipine, and mibefradil.
This invention also relates to a method of treating traumatic brain injury or hypoxic or ischemic stroke in a mammal, including a human, comprising administering to said mammal:
(a) a potassium channel opening compound or a pharmaceutically acceptable salt thereof; and
(b) an NR2B subtype selective NMDA receptor antagonizing compound or a pharmaceutically acceptable salt thereof;
wherein the active agents xe2x80x9caxe2x80x9d and xe2x80x9cbxe2x80x9d above are present in amounts that render the combination of the two agents effective in treating hypoxic or ischemic stroke.
This invention also relates to a pharmaceutical composition for treating traumatic brain injury or hypoxic or ischemic stroke in a mammal, including a human, comprising:
(a) a potassium channel opening compound or a pharmaceutically acceptable salt thereof;
(b) an NR2B subtype selective NMDA receptor antagonizing compound or a pharmaceutically acceptable salt thereof; and
(c) a pharmaceutically acceptable carrier;
wherein the active agents xe2x80x9caxe2x80x9d and xe2x80x9cbxe2x80x9d are present in such composition in amounts that render the combination of the two agents effective in treating such disorder.
Examples of suitable potassium channel openers that can be employed in the methods and pharmaceutical compositions of this invention, as described above, are diazoxide, flupirtine, pinacidil, levcromakalim, rilmakalim, chromakalim, PCO-400 (J. Vasc. Res., November-December 1999, 36 (6), 516-23) and SKP-450 (2-[2xe2x80x3(1xe2x80x3, 3xe2x80x3-dioxolone)-2-methyl]-4-(2xe2x80x2-oxo-1xe2x80x2-pyrrolidinyl)-6-nitro-2H-1-benzopyran).
This invention also relates to a method of treating traumatic brain injury or hypoxic or ischemic stroke in a mammal, including a human, comprising administering to said mammal:
(a) an antiinflammatory compound or a pharmaceutically acceptable salt thereof; and
(b) an NR2B subtype selective NMDA receptor antagonizing compound or a pharmaceutically acceptable salt thereof; wherein the active agents xe2x80x9caxe2x80x9d and xe2x80x9cbxe2x80x9d above are present in amounts that render the combination of the two agents effective in treating hypoxic or ischemic stroke.
This invention also relates to a pharmaceutical composition for treating traumatic brain injury or hypoxic or ischemic stroke in a mammal, including a human, comprising:
(a) an antiinflammatory compound or a pharmaceutically acceptable salt thereof;
(b) an NR2B subtype selective NMDA receptor antagonizing compound or a pharmaceutically acceptable salt thereof; and
c) a pharmaceutically acceptable carrier;
wherein the active agents xe2x80x9caxe2x80x9d and xe2x80x9cbxe2x80x9d are present in such composition in amounts that render the combination of the two agents effective in treating such disorder.
Examples of suitable antiinflammatory compounds that can be employed in the methods and pharmaceutical compositions of this invention, as described above, are NSAIDs, COXII inhibitors, acetominophen and steroidal antiinflammatory agents such as methyl prednilolone and cortisone. Examples of nonsteroidal antiinflamatory drugs (NSAIDs) are diclofenac sodium, nabumetone, naproxen, naproxen sodium, ketorolac, ibuprofen and indomethacin.
Examples of suitable COXII inhibitors that can be employed in the methods and pharmaceutical compositions of this invention are those referred to in the following: U.S. Provisional Patent Application 60/134,311, which was filed on May 14, 1999; U.S. Provisional Patent Application 60/134,312, which was filed on May 14, 1999; U.S. Provisional Patent Application 60/134,309, which was filed on May 14, 1999. The foregoing applications are incorporated herein by reference in their entireties.
Other examples of suitable COXII inhibitors that can be employed in the methods and pharmaceutical compositions of this invention are those referred to in the following: U.S. Pat. No. 5,817,700, issued Oct. 6, 1998; World Patent Application WO97/28121, published Aug. 7, 1997; U.S. Pat. No. 5,767,291, issued Jun. 16, 1998; U.S. Pat. No. 5,436,265, issued Jul. 25 1995; U.S. Pat. No. 5,474,995, issued Dec. 12, 1995; U.S. Pat. No. 5,536,752, issued Jul. 16, 1996; U.S. Pat. No. 5,550,142, issued Aug. 27, 1996; U.S. Pat. No. 5,604,260, issued Feb. 18, 1997; U.S. Pat. No. 5,698,584, issued Dec. 16, 1997; U.S. Pat. No. 5,710,140, issued Jan. 20, 1998; U.S. Pat. No. 5,840,746, issued Nov. 24, 1998; Great Britain Patent Application 986430, filed Mar. 25, 1998; World Patent Application WO97/28120, published Aug. 7, 1997; Great Britain Patent Application 9800689, filed Jan. 14, 1998; Great Britain Patent Application 9800688, filed Jan. 14, 1998; World Patent Application WO94/14977, published Jul. 7, 1994; World Patent Application WO98/43966, published Oct. 8, 1998; World Patent Application WO98/03484, published Jan. 29, 1998; World Patent Application WO98/41516, published Sep. 24, 1998; World Patent Application WO98/41511, published Sep. 24, 1998; Great Britain Patent Application 2,319,032, issued May 13, 1998; World Patent Application WO96/37467, published Nov. 28, 1996; World Patent Application WO96/37469, published Nov. 28, 1996; World Patent Application WO96/36623, published Nov. 21, 1996; World Patent Application WO98/00416, published Jan. 8, 1998; World Patent Application WO97/44027, published Nov. 27, 1997; World Patent Application WO97/44028, published Nov. 27, 1997; World Patent Application WO96/23786, published Aug. 8, 1996; World Patent Application WO97/40012, published Oct. 30, 1997; World Patent Application WO96/19469, published Jun. 27, 1996; World Patent Application WO97/36863, published Oct. 9, 1997; World Patent Application WO97/14691, published Apr. 24, 1997; World Patent Application WO97/11701, published Apr. 3, 1997; World Patent Application WO96/13483, published May 9, 1996; World Patent Application WO96/37468, published Nov. 28, 1996; World Patent Application WO96/06840, published Mar. 7, 1996; World Patent Application WO94/26731, published Nov. 24, 1994; World Patent Application WO94/20480, published Sep. 15, 1994; U.S. Pat. No. 5,006,549, issued Apr. 9, 1991; U.S. Pat. No. 4,800,211, issued Jan. 24, 1989; U.S. Pat. No. 4,782,080, issued Nov. 1, 1988; U.S. Pat. No. 4,720,503, issued Jan. 19, 1988; U.S. Pat. No. 4,760,086, issued Jul. 26, 1988; U.S. Pat. No. 5,068,248, issued Nov. 26, 1991; U.S. Pat. No. 5,859,257, issued Jan. 12, 1999; World Patent Application WO98/47509, published Oct. 29, 1998; World Patent Application WO98/47890, published Oct. 29, 1998; World Patent Application WO98/43648, published Oct. 8, 1998; World Patent Application WO98/25896, published Jun. 18, 1998; World Patent Application WO98/22101, published May 28, 1998; World Patent Application WO98/16227, published Apr. 23, 1998; World Patent Application WO98/06708, published Feb. 19, 1998; World Patent Application WO97/38986, published Oct. 23, 1997; U.S. Pat. No. 5,663,180, issued Sep. 2, 1997; World Patent Application WO97/29776, published Aug. 21, 1997; World Patent Application WO97/29775, published Aug. 21, 1997; World Patent Application WO97/29774, published Aug. 21, 1997; World Patent Application WO97/27181, published Jul. 31, 1997; World Patent Application WO95/11883, published May 4, 1995; World Patent Application WO97/14679, published Apr. 24, 1997; World Patent Application WO97/11704, published Apr. 3, 1997; World Patent Application WO96/41645, published Dec. 27, 1996; World Patent Application WO96/41626, published Dec. 27, 1996; World Patent Application WO96/41625, published Dec. 27, 1996; World Patent Application WO96/38442, published Dec. 5, 1996; World Patent Application WO96/38418, published Dec. 5, 1996; World Patent Application WO96/36617, published Nov. 21, 1996; World Patent Application WO96/24585, published Aug. 15, 1996; World Patent Application WO96/24584, published Aug. 15, 1996; World Patent Application WO96/16934, published Jun. 6, 1996; World Patent Application WO96/03385, published Feb. 8, 1996; World Patent Application WO96/12703, published May 2, 1996; World Patent Application WO96/09304, published Mar. 28, 1996; World Patent Application WO96/09293, published Mar. 28, 1996; World Patent Application WO96/03392, published Feb. 8, 1996; World Patent Application WO96/03388, published Feb. 8, 1996; World Patent Application WO96/03387, published Feb. 8, 1996; World Patent Application WO96/02515, published Feb. 1, 1996; World Patent Application WO96/02486, published Feb. 1, 1996; U.S. Pat. No. 5,476,944, issued Dec. 19, 1995; World Patent Application WO95/30652, published Nov. 16, 1995; U.S. Pat. No. 5,451,604, published Sep. 19, 1995; World Patent Application WO95/21817, published Aug. 17, 1995; World Patent Application WO95/21197, published Aug. 10, 1995; World Patent Application WO95/15315, published Jun. 8, 1995; U.S. Pat. No. 5,504, 215, issued Apr. 2, 1996; U.S. Pat. No. 5,508,426, issued Apr. 16, 1996; U.S. Pat. No. 5,516,907, issued May 14, 1996; U.S. Pat. No. 5,521,207, issued May 28, 1998; U.S. Pat. No. 5,753,688, issued May 19, 1998; U.S. Pat. No. 5,760,068, issued Jun. 2, 1998; U.S. Pat. No. 5,420,343, issued May 30, 1995; World Patent Application WO95/30656, published Nov. 16, 1995; U.S. Pat. No. 5,393,790, issued Feb. 28, 1995; and World Patent Application WO94/27980, published Feb. 8, 1994. The foregoing patents and patent applications are incorporated herein by reference in their entireties.
This invention also relates to a method of treating traumatic brain injury or hypoxic or ischemic stroke in a mammal, including a human, comprising administering to said mammal:
(a) a GABA-A receptor modulator (e.g., a GABA-A receptor agonist) or a pharmaceutically acceptable salt thereof; and
(b) an NR2B subtype selective NMDA receptor antagonizing compound or a pharmaceutically acceptable salt thereof; wherein the active agents xe2x80x9caxe2x80x9d and xe2x80x9cbxe2x80x9d above are present in amounts that render the combination of the two agents effective in treating hypoxic or ischemic stroke.
This invention also relates to a pharmaceutical composition for treating traumatic brain injury or hypoxic or ischemic stroke in a mammal, including a human, comprising:
(a) a GABA-A receptor modulator (e.g., a GABA-A receptor agonist) or a pharmaceutically acceptable salt thereof;
(b) an NR2B subtype selective NMDA receptor antagonizing compound or a pharmaceutically acceptable salt thereof; and
c) a pharmaceutically acceptable carrier;
wherein the active agents xe2x80x9caxe2x80x9d and xe2x80x9cbxe2x80x9d are present in such composition in amounts that render the combination of the two agents effective in treating such disorder.
Examples of suitable GABA-A receptor modulators that can be employed in the methods and pharmaceutical compositions of this invention, as described above, are clomethiazole, and IDDB. Other examples of GABA-A modulators that can be used in the pharmaceutical compositions and methods of this invention are those that are referred to in the following: World Patent Application WO 99/25353, which was published on May 27, 1999; World Patent Application WO 96/25948, which was published on Aug. 29, 1996; World Patent Application WO 99/37303, which was published on Jul. 29, 1999; U.S. Pat. No. 5,925,770, which was issued on Jul. 20, 1999; U.S. Pat. No. 5,216,159, which was issued on Jun. 1, 1993; U.S. Pat. No. 5,130,430, which was issued on Jul. 14, 1992; U.S. Pat. No. 5,925,770, which was issued on Jul. 20, 1999; and World Patent Application WO 99/10347, which was published on Mar. 4, 1999.
This invention also relates to a method of treating traumatic brain injury or hypoxic or ischemic stroke in a mammal, including a human, comprising administering to said mammal:
(a) an antioxidant compound (e.g., alpha-tocopherol) or a pharmaceutically acceptable salt thereof; and
(b) an NR2B subtype selective NMDA receptor antagonizing compound or a pharmaceutically acceptable salt thereof;
wherein the active agents xe2x80x9caxe2x80x9d and xe2x80x9cbxe2x80x9d above are present in amounts that render the combination of the two agents effective in treating hypoxic or ischemic stroke.
This invention also relates to a pharmaceutical composition for treating traumatic brain injury or hypoxic or ischemic stroke in a mammal, including a human, comprising:
(a) an antioxidant compound (e.g., alpha-tocopherol) or a pharmaceutically acceptable salt thereof;
(b) an NR2B subtype selective NMDA receptor antagonizing compound or a pharmaceutically acceptable salt thereof; and
(c) a pharmaceutically acceptable carrier;
wherein the active agents xe2x80x9caxe2x80x9d and xe2x80x9cbxe2x80x9d are present in such composition in amounts that render the combination of the two agents effective in treating such disorder.
Examples of suitable antioxidant compounds that can be employed in the methods and pharmaceutical compositions of this invention, as described above, are vitamin E, vitamin A, calcium dobesilate, stobadine, alpha-tocopherol, ascorbic acid, alpha-lipoic acid, corcumin, catalase, prevastatin, N-acetylcysteine, nordihydroguaiaretic acid, pyrrolidine dithiocarbamate, LY341122, and Metexyl (4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl).
This invention also relates to a method of treating traumatic brain injury or hypoxic or ischemic stroke in a mammal, including a human, comprising administering to said mammal:
(a) an AMPA/kainate receptor antagonizing compound or a pharmaceutically acceptable salt thereof; and
(b) an NR2B subtype selective NMDA antagonizing compound or a pharmaceutically acceptable salt thereof;
wherein the active agents xe2x80x9caxe2x80x9d and xe2x80x9cbxe2x80x9d above are present in amounts that render the combination of the two agents effective in treating hypoxic or ischemic stroke.
This invention also relates to a pharmaceutical composition for treating traumatic brain injury or hypoxic or ischemic stroke in a mammal, including a human, comprising:
(a) an AMPA/kainate receptor antagonizing compound or a pharmaceutically acceptable salt thereof;
(b) an NR2B subtype selective NMDA antagonizing compound or a pharmaceutically acceptable salt thereof; and
(c) a pharmaceutically acceptable carrier;
wherein the active agents xe2x80x9caxe2x80x9d and xe2x80x9cbxe2x80x9d are present in such composition in amounts that render the combination of the two agents effective in treating such disorder.
Examples of suitable AMPA/kainate receptor antagonizing compounds that can be employed in the methods and pharmaceutical compositions of this invention, as described above, are 6-cyano-7-nitroquinoxalin-2,3-dione (CNQX), 6-nitro-7-sulphamoylbenzo[f]quinoxaline-2,3-dione (NBQX), 6,7-dinitroquinoxaline-2,3-dione (DNQX), 1-(4-aminophenyl)-4-methyl-7,8-methylenedioxy-5H-2,3-benzodiazepine hydrochloride and 2,3-dihydroxy-6-nitro-7-sulfamoylbenzo-[f]quinoxaline.
This invention also relates to a method of treating hypoxic or ischemic stroke in a mammal, including a human, comprising administering to said mammal:
(a) a NOS inhibiting compound or a pharmaceutically acceptable salt thereof; and
(b) an NR2B subtype selective NMDA antagonizing compound or a pharmaceutically acceptable salt thereof; wherein the active agents xe2x80x9caxe2x80x9d and xe2x80x9cbxe2x80x9d above are present in amounts that render the combination of the two agents effective in treating hypoxic or ischemic stroke.
This invention also relates to a pharmaceutical composition for treating hypoxic or ischemic stroke in a mammal, including a human, comprising:
(a) a NOS inhibiting compound or a pharmaceutically acceptable salt thereof;
(b) an NR2B subtype selective NMDA antagonizing compound or a pharmaceutically acceptable salt thereof; and
(c) a pharmaceutically acceptable carrier;
wherein the active agents xe2x80x9caxe2x80x9d and xe2x80x9cbxe2x80x9d are present-in such composition in amounts that render the combination of the two agents effective in treating such disorder.
There are three known isoforms of NOSxe2x80x94an inducible form (I-NOS) and two constitutive forms referred to as, respectively, neuronal NOS (N-NOS) and endothelial NOS (E-NOS). Each of these enzymes carries out the conversion of arginine to citrulline while producing a molecule of nitric oxide (NO) in response to various stimuli. It is believed that excess nitric oxide (NO) production by NOS plays a role in the pathology of a number of disorders and conditions in mammals. For example, NO produced by I-NOS is thought to play a role in diseases that involve systemic hypotension such as toxic shock and therapy with certain cytokines. It has been shown that cancer patients treated with cytokines such as interleukin 1 (IL-1), interleukin 2 (IL-2) or tumor necrosis factor (TNF) suffer cytokine-induced shock and hypotension due to NO produced from macrophages, i.e., inducible NOS (I-NOS), see Chemical and Engineering News, December 20, p. 33, (1993). I-NOS inhibitors can reverse this. It is also believed that I-NOS plays a role in the pathology of diseases of the central nervous system such as ischemia. For example, inhibition of I-NOS has been shown to ameliorate cerebral ischemic damage in rats, see Am. J. Physiol., 268, p. R286 (1995)). Suppression of adjuvant induced arthritis by selective inhibition of I-NOS is reported in Eur. J. Pharmacol., 273, p. 15-24 (1995).
NO produced by N-NOS is thought to play a role in diseases such as cerebral ischemia, pain, and opiate tolerance. For example, inhibition of N-NOS decreases infarct volume after proximal middle cerebral artery occlusion in the rat, see J. Cerebr. Blood Flow Metab., 14, p. 924-929 (1994). N-NOS inhibition has also been shown to be effective in antinociception, as evidenced by activity in the late phase of the formalin-induced hindpaw licking and acetic acid-induced abdominal constriction assays, see Br. J. Pharmacol., 110, p. 219-224 (1993). In addition, subcutaneous injection of Freund""s adjuvant in the rat induces an increase in NOS-positive neurons in the spinal cord that is manifested in increased sensitivity to pain, which can be treated with NOS inhibitors, see Japanese Journal of Pharmacology, 75, p. 327-335 (1997). Finally, opioid withdrawal in rodents has been reported to be reduced by N-NOS inhibition, see Neuropsychopharmacol., 13, p. 269-293 (1995).
Examples of NOS inhibiting compounds that can be used in the methods and pharmaceutical compositions of the present invention are those referred to in: U.S. provisional application 60/057094, which was filed Aug. 27, 1997 and is entitled xe2x80x9c2-Aminopyrindines Containing Fused Ring Substituentsxe2x80x9d; the PCT application having the same title that was filed on May 5, 1998, which designates the United States and claims priority from provisional application 60/057094; PCT patent application WO 97/36871, which designates the United States and was published on Oct. 9, 1997; U.S. provisional patent application 60/057739 of John A. Lowe, III, entitled xe2x80x9c6-Phenylpyridin-2-yl-amine Derivativesxe2x80x9d, which was filed on Aug. 28, 1997; PCT patent application PCT/IB98/00112, entitled xe2x80x9c4-Amino-6-(2-substituted-4-phenoxy)-substituted-pyridinesxe2x80x9d, which designates the United States and was filed on Jan. 29, 1998; PCT patent application PCT/IB97/01446, entitled xe2x80x9c6-Phenylpyridyl-2-amine Derivativesxe2x80x9d, which designates the United States and was filed on Nov. 17, 1997; and the U.S. provisional application of John A. Lowe, III, that was filed on Jun. 3, 1998 and is entitled xe2x80x9c2-Aminopyridines Containing Fused Ring Substituentsxe2x80x9d. The foregoing patent applications are incorporated herein by reference in their entirety.
The NR2B subtype selective NMDA antagonists of formula I are readily prepared. The compounds of formula I wherein R2 and R5 are taken together forming a chroman-4-ol ring and R1, R3, and R4 are hydrogen, can be prepared by one or more of the synthetic methods described in U.S. Pat. No. 5,356,905, referred to above. The compounds of formula I wherein R2 and R5 are taken separately and R1, R2, R3 and R4 are hydrogen can be prepared by one or more of the synthetic methods described in U.S. Pat. Nos. 5,185,343, 5,272,160, and 5,338,754, all of which are referred to above. The compounds of formula I can also be prepared by one or more of the synthetic methods described in U.S. patent application Ser. No. 08/292,651,abondoned on Mar. 14, 1995, Ser. No. 08/189,479, abondoned on Dec. 27, 1999, and Ser. No. 09/011,426 now U.S Pat. No. 6,008,233; PCT International Application No. PCT/IB95/00398, which designates the United States (filed May 26, 1995) (corresponding to WO 96/37222); and PCT Application No. PCT/IB95/00380, which designates the United States (filed May 18, 1995) (corresponding to WO 96/06081), all of which are referred to above.
A preferred compound, (1S,2S)-1-(4-hydroxyphenyl)-2-(4-hydroxy-4-phenylpiperidin-1-yl)-1-propanol ((1S,2S) free base), and its tartrate salt, can be prepared as described in U.S. Pat. No. 5,272,160, referred to above. The resolution of racemic 1-(4-hydroxyphenyl)-2-(4-hydroxy-4-phenylpiperidin-1-yl)-1-propanol to form the (1S,2S) free base and the corresponding (1R,2R) enantiomer can be carried out as described in U.S. patent application Ser. No. 09/011,426, now U.S Pat. No. 6,008,233, referred to above, and as exemplified in Example 1 below.
The anhydrous mesylate of the (1S,2S) free base can be prepared as described in U.S. Pat. No. 5,272,160, referred to above. The anhydrous mesylate of the (1S,2S) free base, when equilibrated in an 81% relative humidity environment, will convert to the mesylate salt trihydrate of the (1S,2S) enantiomer.
The mesylate salt trihydrate of (1S,2S)-1-(4-hydroxyphenyl)-2-(4-hydroxy-4-phenylpiperidin-1-yl)-1-propanol can be prepared from the (1S,2S) free base as described in United States provisional patent application entitled xe2x80x9c(1S,2S)-1-(4-Hydroxyphenyl)-2-(4-Hydroxy4-Phenylpiperidin-1-yl)-1-Propanol Methanesulfonate Trihydratexe2x80x9d, referred to above. In this method, (1 S,2S) free base is dissolved in water at 30xc2x0 C. To this solution is added at least 1 equivalent of methane sulfonic acid and the resulting mixture is warmed to 60-65xc2x0 C. The warm solution can be filtered to render it particulate free. The solution is concentrated to approximately 40% of the initial volume, cooled below 10xc2x0 C., isolated by filtration and dried to a water content (measured Karl Fischer titration) of approximately 11.3%. The resulting crystalline mesylate salt trihydrate can be further purified by recrystallization.
Another preferred compound, (3R,4S)-3-[4-(4-fluorophenyl)-4-hydroxy-piperidin-1-yl]-chroman-4,7-diol ((3R,4S) chromanol), can be prepared as described in U.S. Pat. No. 5,356,905, U.S. patent application Ser. No. 08/189,479, abandonded on Dec. 27, 1994, and United States provisional patent application entitled xe2x80x9cProcess For The Resolution of Cis-Racemic 7-Benzyloxy-3-[4-(4-Fluorophenyl)-4-Hydroxy-Piperidin-1-yl]-Chroman-4-ol Dibenzoyl-D-Tartratexe2x80x9d, all three of which are referred to above. The starting materials and reagents required for the synthesis of the (3R,4S) chromanol are readily available, either commercially, according to synthetic methods disclosed in the literature, or by synthetic methods exemplified in the description provided below.
The (3R,4S) chromanol can be prepared by fractional crystallization of the L-proline ester of racemic cis-7-benzyloxy-3-[4-(4-fluorophenyl)4-hydroxy-piperidin-1-yl]-chroman-4-ol, as described in U.S. patent application Ser. No. 08/189,479 abandonded on Dec. 27, 1994, referred to above. In a preferred method, the resolution method described in United States provisional patent application entitled xe2x80x9cProcess For The Resolution Of Cis-Racemic 7-Benzyloxy-3-[4-(4-Fluorophenyl)-4-Hydroxy-Piperidin-1-yl]-Chroman-4-ol Dibenzoyl-D-Tartratexe2x80x9d, referred to above, and as exemplified in Example 3. In this method, the parent chromanol is prepared by dissolving racemic cis-7-benzyloxy-3-[4-(4-fluorophenyl)-4-hydroxy-piperidin-1-yl]-chroman-4-ol with an equal molar amount of dibenzoyl-D-tartaric acid in boiling aqueous ethanol. Racemic cis-7-benzyloxy-3-[4-(4-fluorophenyl)-4-hydroxy-piperidin-1-yl]-chroman-4-ol is prepared as described in U.S. patent application Ser. No. 08/189,479, referred to above. The concentration of aqueous ethanol is not critical and may be varied between 75% and 95% ethanol (ETOH). A concentration of 9:1/ETOH:H2O has been found to be effective and is preferred. A sufficient amount of the aqueous ethanol solvent to dissolve the racemic compound is required. This amount has been found to be about 17 ml per gram of racemic compound.
Upon stirring while heating under reflux, the racemic compound dissolves to form a hazy solution which is allowed to cool with stirring whereupon the (+) isomer, (3R,4S)-7-benzyloxy-3-[4-(4-fluorophenyl)-4-hydroxy-piperidin-yl]-chroman-4-ol dibenzoyl-D-tartrate, precipitates and may be collected by filtration and washed with aqueous ethanol. This is the tartrate salt of the (3R,4S) chromanol. The lactate and mandelate salts of the (3R,4S) chromanol are prepared in an analogous manner. This initial product is of about 90% optical purity. If a higher purity is desired, the product may be heated again with aqueous ethanol, cooled and the product collected and washed. Two such treatments were found to yield the (+) isomer of 99.4% optical purity in an overall yield of 74%. This procedure is preferred over the procedure described in U.S. patent application Ser. No. 08/189,479, referred to above, in that it avoids a reduction step with lithium aluminum hydride and is therefore more suitable for bulk operations. This procedure also produces a significantly higher yield of the desired product.
The above described (+) isomer can be converted to (3R,4S)-3-[4-(4-fluorophenyl)-4-hydroxy-piperidin-1-yl]-chroman-4,7-diol by standard procedures. For example, treatment with dilute base can be used to free the piperidinyl base and subsequent hydrogeneration removes the 7-benzyl group to yield the (3R,4S) chromanol.
In general, the pharmaceutically acceptable acid addition salts of the compounds of formula I can readily be prepared by reacting the base forms with the appropriate acid. When the salt is of a monobasic acid (e.g., the hydrochloride, the hydrobromide, the p-toluenesulfonate, the acetate), the hydrogen form of a dibasic acid (e.g., the dihydrogen phosphate, the citrate), at least one molar equivalent and usually a molar excess of the acid is employed. However, when such salts as the sulfate, the hemisuccinate, the hydrogen phosphate or the phosphate are desired, the appropriate and exact chemical equivalents of acid will generally be used. The free base and the acid are usually combined in a co-solvent from which the desired salt precipitates, or can be otherwise isolated by concentration and/or addition of a non-solvent.
As indicated above, selectivity of compounds for the NR2B-subunit containing NMDA receptor is defined as an affinity for the racemic [3H](+)-(1S, 2S)-1-(4-hydroxy-phenyl)-2-(4-hydroxy-4-phenylpiperidino)-1-propanol binding site in forebrain of rats, as described in Chenard and Menniti (Antagonists Selective for NMDA receptors containing the NR2B Subunit, Current Pharmaceutical Design, 1999, 5:381-404). This affinity is assessed in a radioligand binding assay as described below. Selective compounds are those which displace specific binding of racemic [3H]CP-101,606 from rat forebrain membranes with an IC50xe2x89xa65 xcexcM.
The binding of racemic [3H] (+)-(1S, 2S)-1-(4-hydroxy-phenyl)-2-(4-hydroxy-4-phenylpiperidino)-1-propanol to rat forebrain membranes is measured as described by Menniti et al. (CP-101,606, a potent neuroprotectant selective for forebrain neurons, European Journal of Pharmacology, 1997, 331:117-126). Forebrains of adult male CD rats are homogenized in 0.32M sucrose at 4xc2x0 C. The crude nuclear pellet is removed by centrifugation at 1,000xc3x97g for 10 minutes, and the supernatant centrifuged at 17,000xc3x97g for 25 minutes. The resulting pellet is resuspended in 5 mM Tris acetate pH 7.4 at 4xc2x0 C. for 10 minutes to lyse cellular particles and again centrifuged at 17,000xc3x97g. The resulting pellet is washed twice in Tris acetate, resuspended at 10 mg protein/ml and stored at xe2x88x9220xc2x0 C. until use.
For binding assays, membranes are thawed, homogenized, and diluted to 0.5 mg protein/ml with 50 mM Tris HCl, pH 7.4. Compounds under study are added at various concentrations followed by racemic [3H] (+)-(1S, 2S)-1-(4-hydroxy-phenyl)-2-(4-hydroxy-4-phenylpiperidino)-1-propanol (specific activity 42.8 Ci/mmol, 5 nM final concentration). Following incubation for 20 min at 30xc2x0 C. in a shaking water bath, samples are filtered onto Whatman GFB glass fiber filters using a MB-48R Cell Harvester (Brandel Research and Development Laboratories, Gaithersburg Md.). Filters are washed for 10 s with ice cold Tris HCl buffer and the radioactivity trapped on the filter quantified by liquid scintillation spectroscopy. Nonspecific binding is determined in parallel incubations containing 100 xcexcM racemic (+)-(1S, 2S)-1-(4-hydroxy-phenyl)-2-(4-hydroxy-4-phenylpiperidino)-1-propanol. Specific binding is defined as total binding minus nonspecific binding.
Compounds of the formula I have selectivity for NR2B subunit-containing NMDA receptors over xcex11-adrengergic receptors. Affinity for the NR2B subunit containing NMDA receptor is measured as the IC50 for displacement of specific binding of racemic [3H] (+)-(1S, 2S)-1-(4-hydroxy-phenyl)-2-(4-hydroxy4-phenylpiperidino)-1-propanol from rat forebrain membranes (described above). Affinity for the xcex11-adrengergic receptor is defined as the IC50 for displacement of specific binding of racemic [3H]prazosin from rat brain membranes, measured as described by Greengrass and Bremner (Binding Characteristics of [3H]prazosin to Rat Brain xcex1-Adrenergic Receptors, European Journal of Pharmacology, 55, 323-326, (1979)). A compound with a ratio of ([3H]prazosin/[3H] (+)-(1S, 2S)-1-(4-hydroxy-phenyl)2-(4-hydroxy-4-phenylpiperidino)-1-propanol) affinity greater than three is considered selective.
Forebrains of adult male Sprague Dawley rats are homogenized in 20 volumes of ice cold 50 mM Tris/HCl buffer (pH 7.7). The homogenate is centrifuged at 50,000xc3x97g for 10 minutes at 4xc2x0 C. The pellet is resuspended and centrifuged under identical conditions and the final pellet is resuspended in 80 volumes of 50 mM Tris/HCl (pH 8.0) at 4xc2x0 C.
For binding assays, compounds under study are added at various concentrations to 500 xcexcg membrane protein in 1 ml of 50 mM Tris/HCl buffer, followed by [3H]prazosin (Amersham, specific activity 33 Ci/mmol, 0.2 nM final concentration). Following incubation for 30 min at 25xc2x0 C. in a shaking water bath, samples are filtered onto Whatman GFB glass fiber filters using a MB-48R Cell Harvester (Brandel Research and Development Laboratories, Gaithersburg Md.). Filters are washed three times for 10s with ice cold Tris HCl buffer and the radioactivity trapped on the filter quantified by liquid scintillation spectroscopy. Nonspecific binding is determined in parallel incubations containing 100 nM prazosin. Specific binding is defined as total binding minus nonspecific binding.
NR2B selective NMDA receptor antagonists useful in the practice of the invention may also be used in the form of a pharmaceutically acceptable salt. The expression xe2x80x9cpharmaceutically-acceptable acid addition saltsxe2x80x9d is intended to include but not be limited to such salts as the hydrochloride, hydrobromide, sulfate, hydrogen sulfate, phosphate, hydrogen phosphate, dihydrogenphosphate, acetate, succinate, citrate, tartrate, lactate, mandelate, methanesulfonate (mesylate) and p-toluenesulfonate (tosylate) salts. The acid addition salts of the compounds of the present invention are readily prepared by reacting the base forms with the appropriate acid. When the salt is of a monobasic acid (e.g., the hydrochloride, the hydrobromide, the p-toluenesulfonate, the acetate), the hydrogen form of a dibasic acid (e.g., the hydrogen sulfate, the succinate) or the dihydrogen form of a tribasic acid (e.g., the dihydrogen phosphate, the citrate), at least one molar equivalent and usually a molar excess of the acid is employed. However when such salts as the sulfate, the hemisuccinate, the hydrogen phosphate or the phosphate are desired, the appropriate and exact chemical equivalents of acid will generally be used. The free base and the acid are usually combined in a co-solvent from which the desired salt precipitates, or can be otherwise isolated by concentration and/or addition of a non-solvent.
Assays that can be used to determine the neutrophil inhibiting activity of a substance are described in U.S. Pat. No. 5,919,900, referred to above.
NMDA receptor antagonists, and, in particular, NR2B selective NMDA receptor antagonists, can also be administered in combination with a selective serotonin reuptake inhibitor (SSRI). Examples of selective serotonin reuptake inhibitors that can be administered, either as part of the same pharmaceutical composition or in a separate pharmaceutical composition, with an NR2B selective NMDA receptor antagonist, include: fluoxetine, fluvoxamine, paroxetine and sertraline, and pharmaceutically acceptable salts thereof.
This invention relates both to methods of treatment in which the NMDA antagonist and the other active ingredient in the claimed combinations are administered together, as part of the same pharmaceutical composition, as well as to methods in which the two active agents are administered separately, as part of an appropriate dose regimen designed to obtain the benefits of the combination therapy. The appropriate dose regimen, the amount of each dose administered, and the intervals between doses of the active agents will depend upon the particular NMDA antagonist and other active ingredient being used in combination, the type of pharmaceutical formulation being used, the characteristics of the subject being treated and the severity of the disorder being treated.
Generally, in carrying out the methods of this invention, COX-2 inhibitors will administered to an average adult human in amounts ranging from about 5 to about 300 mg per day, depending on the COX-2 inhibitor, severity of the headache and the route of administration. NSAIDS, in carrying out the methods of this invention, will generally be administered to an average adult human in amounts ranging from about 7 to about 2,000 mg per day. NMDA receptor antagonists, including glycine site antagonists, in carrying out the methods of this invention, will generally be administered to an average adult human in amounts ranging from about 25 to about 1500 mg per day.
NIF""s, in carrying out the methods of this invention, will generally be administered to an average adult human in amounts ranging from about 0.1 to about 140 mg/kg body weight/per day.
Calcium channel antagonists, potassium channel openers, sodium channel antagonists, and antioxidants, in carrying out the methods of this invention, will generally be administered to an average adult human in amounts within the ranges used when such agents are administered, respectively, as single active pharmaceutical agents. Such dosages are available in the scientific and medical literature, and, for substances that have been approved for human use by the Food and Drug Administration, in the current edition (presently the 53rd edition) of the Physician""s Desk Reference, Medical Economics Company, Montvale, N.J.
In some instances, dosage levels below the lower limit of the aforesaid range may be more than adequate, while in other cases still larger doses may be employed without causing any harmful side effects, provided that such higher dose levels are first divided into several small doses for administration throughout the day.
The pharmaceutically active agents used in the methods and pharmaceutical compositions of this invention can be administered orally, parenterally, or topically, alone or in combination with pharmaceutically acceptable carriers or diluents, and such administration may be carried out in single or multiple doses. More particularly, the therapeutic agents of this invention can be administered in a wide variety of different dosage forms, i.e., they may be combined with various pharmaceutically acceptable inert carriers in the form of tablets, capsules, lozenges, troches, hard candies, powders, sprays, creams, salves, suppositories, jellies, gels, pastes, lotions, ointments, aqueous suspensions, injectable solutions, elixirs, syrups, and the like. Such carriers include solid diluents or fillers, sterile aqueous media and various non-toxic organic solvents, etc. Moreover, oral pharmaceutical compositions can be suitably sweetened and/or flavored. In general, the therapeutically-effective compounds of this invention are present in such dosage forms at concentration levels ranging from about 5.0% to about 70% by weight.
For oral administration, tablets containing various excipients such as microcrystalline cellulose, sodium citrate, calcium carbonate, dicalcium phosphate and glycine may be employed along with various disintegrants such as starch (and preferably corn, potato or tapioca starch), alginic acid and certain complex silicates, together with granulation binders like polyvinylpyrrolidone, sucrose, gelatin and acacia. Additionally, lubricating agents such as magnesium stearate, sodium lauryl sulfate and talc are often very useful for tabletting purposes. Solid compositions of a similar type may also be employed as fillers in gelatin capsules; preferred materials in this connection also include lactose or milk sugar as well as high molecular weight polyethylene glycols. When aqueous suspensions and/or elixirs are desired for oral administration, the active ingredient may be combined with various sweetening or flavoring agents, coloring matter or dyes, and, if so desired, emulsifying and/or suspending agents as well, together with such diluents as water, ethanol, propylene glycol, glycerin and various like combinations thereof.
For parenteral administration, solutions of a pharmaceutically active agent used in accordance with this invention in either sesame or peanut oil or in aqueous propylene glycol may be employed. The aqueous solutions should be suitably buffered (preferably pH greater than 8) if necessary and the liquid diluent first rendered isotonic. These aqueous solutions are suitable for intravenous injection purposes. The oily solutions are suitable for intra-articular, intramuscular and subcutaneous injection purposes. The preparation of all these solutions under sterile conditions is readily accomplished by standard pharmaceutical techniques well known to those skilled in the art.
Additionally, it is also possible to administer the active agents used in accordance with the present invention topically, and this may be done by way of creams, jellies, gels, pastes, patches, ointments and the like, in accordance with standard pharmaceutical practice.
Certain NMDA antagonists of the formula I are illustrated by the following examples.
All nonaqueous reactions were run under nitrogen for convenience and generally to maximize yields. All solvents/diluents were dried according to standard published procedures or purchased in a predried form. All reactions were stirred either magnetically or mechanically. NMR spectra are recorded at 300 MHz and are reported in ppm. The NMR solvent was CDCl3 unless otherwise specified. IR spectra are reported in cmxe2x88x921, generally specifying only strong signals.